This invention relates generally to a lamp-starting device and to improvements in a device of this type in which means located in the circuit applies less than rated voltage to the lamp when the lamp is initially energized, and means in the circuit completely electrically bypasses the first said means in the circuit and applies substantially rated voltage to the lamp after the lamp is heated. More particularly, a temperature-actuated mercury switch is a component part so that a resistor is either completely in or out of the lamp circuit, the mercury switch being operated by conductive heat from the lamp socket.
The prior conventional lamp-starting devices utilized a negative temperature coefficient resistor in series with the lamp, the resistor being heated by current passing through the resistor. With this type of device, the resistance in the circuit decreases as the temperature of the negative temperature coefficient resistor increases. Accordingly, the resistor is at all times in circuit with the lamp.